Changes in Demodex Positivity Before and During the Coronavirus Disease 2019 Pandemic and the Potential Influence of Pandemic-Related Factors

Abstract

Objective: We aimed to compare Demodex positivity before and during the coronavirus disease 2019 pandemic. Methods: Patients who underwent a standardized skin surface biopsy and direct microscopic examination for Demodex species in the prepandemic or pandemic period at a tertiary care center were included. The positivity rates in the two periods were compared across age, sex, and months using a proportional Z-test. A p value <0.05 was considered statistically significant. Results: In total, 573 and 523 patients were included in the pandemic and prepandemic periods, respectively. Demodex positivity was significantly higher in the pandemic period (68.9%) than in the prepandemic period (50.5%) (p < 0.00001). Demodex positivity increased significantly among male (p = 0.00386) and female groups (p < 0.00001) in the pandemic period compared with that in the prepandemic period. Positivity rates increased in all age groups, with significant increases observed in those aged 10-25 (p = 0.00006), 36-45 (p = 0.0012), and 46-55 (p = 0.01242) years. Conclusion: Demodex positivity was higher in the pandemic period than in the prepandemic period, with significant increases observed during colder months. Furthermore, the increase in positivity was most prominent in patients aged 10-25 years, who spend more time in schools or crowded work places. Therefore, a possible association of face mask use and higher Demodex positivity must be explored through future controlled studies.